Xenon, Xe-133

XENON, XE-133- xenon xe-133 gas
Mallinckrodt Inc.

DESCRIPTION

Xenon Xe 133 Gas is for diagnostic inhalation use only. It is supplied in vials containing either 370 or 740 megabecquerels (10 or 20 millicuries) of Xenon Xe 133 Gas in 2 milliliters of carrier xenon and atmospheric air.

Xenon Xe 133 Gas is chemically and physiologically similar to elemental xenon, a non-radioactive gas which is physiologically inert except for anesthetic properties at high doses.

Xenon Xe 133 is produced by fission of Uranium U 235. At the time of calibration, it contains no more than 0.3% Xenon Xe 133m, no more than 1.5% Xenon Xe 131m, no more than 0.06% Krypton Kr 85 and no more than 0.01% Iodine I 131, with no less than 99.9% total radioactivity as radioxenon. Table 1 shows the effect of time on radionuclidic composition.

Table 1. Radionuclidic Composition

*

Calibration Date

Expiration Date

Percent of Total Radioactivity

Days

% Xe-133

% Xe-133m

% Xe-131m

% Kr-85

% I-131

-5

>98.3

<0.6

<1.0

<0.03

<0.01

0*

>98.1

<0.3

<1.5

<0.06

<0.01

7

>97.2

<0.08

<2.5

<0.15

<0.02

14

>95.7

<0.02

<4.1

<0.37

<0.02

PHYSICAL CHARACTERISTICS

Xenon Xe 133 decays by beta and gamma emissions with a physical half-life of 5.245 days.1 Photons that are useful for detection and imaging studies as well as the principal beta emission are listed in Table 2.

Table 2. Principal Radiation Emission Data

Radiation

Mean % Per

Disintegration

Energy

(keV)

Beta-2

99.3

100.6 Avg.

Gamma-2

36.5

81.0

K alpha x-rays

38.9

30.8 Avg.

K beta x-rays

9.1

35.0 Avg.


1

Kocher, David C., &apos;Radioactive Decay Data Tables,&apos; DOE/TIC-11026, 138 (1981).

EXTERNAL RADIATION

The specific gamma ray constant for Xenon Xe 133 is 0.51 R/hr-mCi at 1 cm. The first half-value thickness is 0.0035 cm of Pb.

A range of values for the relative attenuation of the radiation emitted by this radionuclide that results from interposition of various thicknesses of Pb is shown in Table 3. For example, the use of 0.2 cm of Pb will decrease the external radiation exposure by a factor of about 1000.

Table 3. Radiation Attenuation by Lead Shielding

Shield

Thickness (Pb), cm

Coefficient

of Attenuation

0.0035

0.5

0.037

10-1

0.12

10-2

0.20

10-3

0.29

10-4

To correct for physical decay of this radionuclide, the fractions that remain at selected time intervals after the date of calibration are shown in Table 4.

Table 4. Physical Decay Chart; Xenon Xe 133, Half-life 5.245 Days

*

Calibration Date

Days

Fraction

Remaining

Days

Fraction

Remaining

0*

1.000

8

0.347

1

0.876

9

0.304

2

0.768

10

0.267

3

0.673

11

0.234

4

0.589

12

0.205

5

0.516

13

0.179

6

0.453

14

0.157

7

0.397


Page 1 of 3 1 2 3

All MedLibrary.org resources are included in as near-original form as possible, meaning that the information from the original provider has been rendered here with only typographical or stylistic modifications and not with any substantive alterations of content, meaning or intent.

This site is provided for educational and informational purposes only, in accordance with our Terms of Use, and is not intended as a substitute for the advice of a medical doctor, nurse, nurse practitioner or other qualified health professional.

Privacy Policy | Copyright © 2020. All Rights Reserved.